Revetment



May 14 1935v J. R. FoRDYcE 2,001,13@

. REVETMENT Filed Deo. 3, 1952 ,.river banks,vcanals and irrigationparticularly to revetment mats and f invention relates generally toPaten-rea 'May 14, ieee anni@ REVETMEN'I a John R. Fordyce, Hot Springs,Ark. Application December 3, 1932, Serial'No. 646,471

il Claims. a the protection of revetments such, for instance, as levees,ditches, and l the Kmethod of making and applying the same to therevetment. .A Y

In 'the protection of revetments, it has heretofore been the practice tolaunch and suitably secure to the banks, mats which may be formed ofbundles of willows woven together as by means of wire cables. Someattempts have been made to provide a `series of concrete slabs suitablysecured together so as to provide a revetment mat Land it has also beenattempted to provide such mats in whichv a lfor instance, asphalt oil isused in compositions permanently flexible binder as,

with stone, sand .and the like, and provided with suitablere-enforcements to form revetment mats'.

'Mats wherein asphaltic oils and similar materials are employed, so asto render the mat per- Y Vmanently exible, are, however, of relativelyshort life due to the fact that the asphaltic oil or other fluid binderis readily scoured out of the compo-I sition by the current of thestream and by the sand which is carried by it so that such mats are Aofextremely short eiective life. A

4readily conform itself to the 30' The object of the v presentinvention, generally stated, is to provide a revetment mat which willcontour ofthe revetmentv or stream bank upon being launched, but whichis of such character as to resist the a -erosive action of the water.

- A further object of this invention is to provide a revetment mat and amethod of applying the same whereby the mat, although soft when v`l 1' ilaunched; will harden upon exposure to the water so as to form a hardandresistant protection to the stream bank.

Amore specific object of this invention is to provide a revetment matwherein the binder emvthis invention.

In accordance with the present invention generally stated, a suitablewater prooiing binder material such, for instanca'asn asphalticsubstance which is hard and resistant under ordinary Vconditions butwhich may be softened for Work-y d5 ing may have incorporated with it asuitable quan- (Cll. Sli-38) tity of mineral aggregate such, forinstance, as gravel, sand, broken stone of silicious, argillaceous orcalcareous nature, or if desired, of aclass of heavy mineral substancessuch, for instance, as barite or hematite. The aggregate should, of 5course, be so selected as to size as to produce a matrix having amaximum specific gravity and a low percentage of voids. In the matrixresulting from the mixture of asphaltic substance and mineral aggregateas just described, may be embedded l0 a series of suitable metallicre-enforcements which may be in the form of wire mesh, interwovencables, expanded metal or other suitable re-enforcements, preferablyflexible. In accordance with the present invention, the asphalticsubstance which at ordinary temperatures is nrmally hard, may be heatedto a temperature substantially above its softeningipoint so as to renderthe same workable and While maintained at this temperature may beincorporated with the aggregate and have the metallic re-enforcementsembedded in'it. Furthermore before the temperature of` the asphalticsubstance drops below the softening point, the resultant re-enforced matis, in accordance with the present invention, launched into the streamand secured to the revetment. In this manner advantage is taken of theexibility of the asphaltum while at the elevated temperatures so thatthe mat may conform itself to the contour of the revetment, but uponexposure to the water it will be understood that the asphaltum will coolbelow its softening point so as to present a hard resistant mat whichwill eciently protect the 'banks of the stream and be of substantiallife.

As a specific illustration of a practical embodiment of the invention,the binder material selected may be asphaltum which is hard at ordinarytemperatures and little aiected by water or climatic temperaturechanges, but which may 40 be softened at about 150F. A suitable quantityof such asphaltu'm, for instance, sumcient to comprise 20% of the matrixto be formed may be heated to a workable temperature as, for instance,about 350 F.

A suitable quantity of mineral aggregate, for instance, sumcient tocomprise about 80% of the matrix to be formed, may, after beingcarefully graded and Washed, be heated to a temperature approaching theworking temperature of the asphaltu'm as, for instance 300 F. When themineral aggregate is heated to this extent, it will be understood thatthe same may be incorporated with the asphaltum without cooling thelatter to an extent such that it will become unworkable.

50 stream banks to formed into sheets or slabs while the asphaltum ismaintained at a working temperature. The platform may be dusted overwith limestone dust, talc or Portland cement in order to prevent theasphaltum from sticking thereto. Across the platform the metallicre-enforcements, which may be in the form of a metallic mesh or fabric,may be spread and on to this the desired quantity of theasphaltumaggregate mixture, after being thoroughly incorporated, as in apug mill, may be spread. Enough of the asphaltum aggregate mixture maybe spread to form a sheet or slab of the desired thickness and themixture may then be compacted about the re-enforcements, as by tampingor rolling to an extent'suiilcient that the mixture entirely surrounds'and encloses; the reenforcements so as to form a water p roofcoherentmass. It will be understood thatf'duringrallthese operations thetemperature ofthe asphaltum aggregate mixture is maintained fabove'thelsoftening point for the asphaltum and preferably suf-` ciently highthat the asphaltum may completely coat the metallic reenforcement so thesame from corrosion.

Before the sheet or slab thus formed has cooled below the softeningpoint for the asphaltum and preferably while the same is at atemperature considerably above that point, the sheet or slab may belaunched or applied to the revetment or stream bank. In accordance withthe present invention the temperature of the slab o r sheet ispreferably at this time sufficiently above the softening temperature forthe asphaltum that the slab or sheet may sink into position beneath thewater and conform itself to the contour of the revetment or stream bankbefore hardening.

When theaggregate employed is of a heavy mineral such, for instance, asa class including barite and hematite, itis apparent that the sheets orslabs formed in accordance with the present invention may be caused tosink beneath the surface ofthe water without the use of extraneousmeans, the specic gravity of the mineral' being sufhcient to sink it andmaintain the same against displacement bythe stream current. It will beunderstood, of course, formed of lighter minerals and the sheets orslabs suitably anchored or otherwise secured to the preventdisplacement.

It will be understood that the amount of asphaltum may be varied inaccordance with the requirements of a particular stream and the size ofthe aggregate employed, as from.5% to 25%Y by weight of the mat. Thethickness of the mat may be varied' from one-half to six inches,depending upon stream conditions and the character of materialsemployed. As pointed out hereinbefore, a sufdcient quantity of asphaltumis preferably employed'to completely coat the metallic re-enforcement soas to protect the same from corrosion and, if other metallicre-enforcement may be given a pre-coat of asphaltum. l

as to protect that the mats may be` desired, the wire mesh or It will beunderstood that the metallic re-en forcement employed may be of anysuitable character, preferably of sumcient flexibility to permit the matto adaptitself to the contour of the revetment or stream bank.

From the foregoing description it is apparent that the present inventioncontemplates a method of protecting revetments wherein the mat employedis of such composition as to effectively resist the erosive action ofthe sand carriedA by a stream and that the revetment mat of the presentinvention, although sufficiently pliable to conform itself to thecontour of the stream bank at the time of launching, will immediatelybecome sufficiently hard to se resistant. It is 'apparent that manymodifications of the revetment mat` and the process of making andapplying the same, hereinbefore described will occur to those skilled inthe ant which will not depart from the spirit of this invention. Itis'to be distinctly understood, therefore, that the invention is notlimited t0 the specic details hereinbefore described for the purpose ofillustration, tions and the use of such sub-combinations of features asdo not depart' from the spirit of this invention are, although notspecifically described herein, contemplated by and within the scope ofthe appended claims.-

Having thus described the invention, what is claimed is:r

l. In the art ofl protecting revetments, the process comprisingfheatingnormally hard asphaltum to a temperature substantially above itssoftening point, mixing mineral aggregate with the asphaltum, workingthe 'hot asphaltum-aggregate mixture about a substantially fiatreenforcing network to form a selfsustaining sheet, and launching thesheet before the mixture cools to below the hardening temperature.

2. In the art of protecting revetments, the process comprising, heatingnormally hard asphaltum to a temperature of about 350 F., preheating amineral aggregate to a temperature of about 300 F., incorporating thehot asphaltum and aggregate, workingA the hot mixture around areenforcing network to form a self-sustaining sheet, and launching thesheet.

3. A revetment mat comprising a matrix of a mineral aggregate in avbinder of normally hard asphalt which is resistant to water anderosion, and a reinforcing structure embedded in and completely enclosedby said matrix, said reinforced matrix being in the form ofself-sustaining sheets.

4. A revetment mat comprising a self-sustaining sheet preformed so as tobe launched upon the bank of a stream, said mat composed of a metallicreinforcement imbedded in and vcompletely enclosed by,a matrixA ofnormally hard asphalt and mineral aggrega I the asphalt being of suchcharacter as to form aA permanently hard surface at atmospherictemperatures.

JOHN R. FORDYCE.

individual features and but that such modiflca-

